noun

• (countable, uncountable) The act of contradicting.
• (countable) A statement that contradicts itself, i.e., a statement that claims that the same thing is true and that it is false at the same time and in the same senses of the terms.
• (countable) A logical inconsistency among two or more elements or propositions.
• (logic, countable) A proposition that is false for all values of its propositional variables or Boolean atoms.